AllReduce Stalls Are Network Stalls. Most Tools See Neither.
The article discusses the relationship between AllReduce stalls and network performance in multi-node GPU training jobs. It highlights how slow AllReduce operations can often be attributed to TCP retransmits rather than GPU performance issues. The author provides insights into monitoring tools and methods for diagnosing these stalls effectively.
- ▪A slow AllReduce operation can indicate network stalls rather than GPU issues.
- ▪The article explains how to use monitoring tools to identify the causes of slow AllReduce calls.
- ▪TCP retransmits are a common reason for slow AllReduce performance in multi-node setups.
Opening excerpt (first ~120 words) tap to expand
try { if(localStorage) { let currentUser = localStorage.getItem('current_user'); if (currentUser) { currentUser = JSON.parse(currentUser); if (currentUser.id === 3853036) { document.getElementById('article-show-container').classList.add('current-user-is-article-author'); } } } } catch (e) { console.error(e); } Ingero Team Posted on May 27 • Originally published at ingero.io AllReduce Stalls Are Network Stalls. Most Tools See Neither. #machinelearning #devops #performance #networking A slow AllReduce on rank 5 lines up against TCP retransmits on rank 5’s NIC, four ms before the collective completes.
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